AD604

Rev. D | Page 25 of 32

Connecting the DSX Inputs to the Preamplifiers

To connect the DSX inputs to the preamplifiers, install jumpers

in the JP6 lower position and in JP15. Verify that the jumpers in

JP13 and JP14 are removed.

Cascaded DSX

To channel cascade the two channels, insert a jumper in JP13.

The resulting single channel gain range is 96 dB. Verify that

JP14 and JP15 are removed.

The gains of cascaded VGAs can be controlled independently

or in common. For common control, insert a jumper in the top

position of JP4. To use the trimmer as a gain control, insert a

jumper in JP1. For external control, remove JP1 and connect a

signal source at test loop VGN1 or VGN2.

PREAMPLIFIER GAIN

Jumpers in JP7 and JP12 select between two preamplifier gains:

14 dB and 20 dB. Intermediate gains are derived by installing

resistors in positions R11 and R12. The 14 dB and 20 dB preset

gains are accurate due to close matching of thin film resistors.

The gain accuracy after installing external resistors is subject to

inherent tolerance of absolute accuracy.

OUTPUTS

The DSX outputs are available on OUT1 and OUT2 SMA

connectors and are series terminated with decoupling capacitors

and 49.9 Ω series resistors. These components can be replaced

to accommodate other output impedances.

DC OPERATING CONDITIONS

Table 4 lists the trimmers and their functions provided for

convenient dc level adjustments of gain, reference voltage,

and output common-mode voltage. Table 5 lists the jumpers

and their functions.

Table 4. Trimmer Functions

Trimmer

Function

R1

Gain of Channel 1

R2

Reference voltage adjustment

R3

Output common-mode voltage adjustment

R4

Channel 2 gain adjustment

Table 5. Jumpers

Jumper No.

Function

1

Connects R1 gain adjust wiper to VGN1

2

Connects R2 reference voltage trimmer to VREF input

3

Connects common-mode voltage trimmer to VOCM

4

Connects VGN2 to R4 Channel 2 gain trimmer or to VGN1 or common gain adjustment

5

Connects –DSX1 to CH1 VGA IN (−) or to ground

6

Connects +DSX1 (ac-coupled) to preamplifier output of Channel 1 or to the CH 1 VGA IN (+) SMA connector

7

When open, the Preamp 1 Gain is 20 dB; Preamp Gain 1 is 14 dB when a shunt is installed

8

Shunt in left position disables Preamp 1; shunt in rightmost position enables Preamp 1

9

Shunt in left position disables Preamp 2; shunt in rightmost position enables Preamp 2

12

When open, the Preamp 2 gain is 20 dB; Preamp 2 gain is 14 dB when a shunt is installed

13

Cascades DSX2 with DSX 1 when a jumper is inserted

14

Connects +DSX2 (ac-coupled) to preamplifier output of Channel 2 or to the CH 2 VGA IN (+) SMA connector

15

Connects +DSX2 (ac-coupled) to preamplifier output of Channel 2

16

Connects –DSX2 to CH2 VGA IN (−) or to ground